To enable the efficient elimination or controlling of unwanted plants, it is desirable to use effective chemical formulations of herbicides. Compositions containing two or more herbicides are desirable in agricultural, specialty applications and related endeavors due to broadening the spectrum or range of unwanted plant species killed or controlled.
Due to the desirability of having a composition with the above-mentioned properties, it is useful to use combinations of herbicides to obtain enhanced control of numerous weeds with a single application. Combinations of pesticides are known and available as mixed solutions of the active ingredients in their commercially available formulations. One method of preparing such a composition is referred to as “tank mixing” in which the ingredients in their commercially available form are mixed together by the user in a quantity of water. Tank mixes require the end user to purchase two or more commercial formulations, store them, calculate the correct amount of each active ingredient, measure those amounts into the mix and when empty, properly dispose of a number of containers. Combining the active ingredients into one formulation is beneficial but frequently more complex due to widely different physical properties of the active ingredients in which chemical and physical stability are problems.
Sulfentrazone, the common name for N-[2,4-dichloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl]phenyl]methanesulfonamide, a highly effective post-emergence herbicide, chemically degrades in the presence of water. Glyphosate, the common name for N-(phosphonomethyl)glycine, is a most effective pre and post-emergence herbicide especially when applied as a salt of glyphosate, for example, the isopropylamine salt. Glyphosate salts are water-soluble and are normally formulated in an aqueous medium.
Co-formulations containing sulfentrazone and a glyphosate salt are known. For example, U.S. Pat. No. 6,713,433 discloses an oil-in-water microemulsion of sulfentrazone, using volatile organic solvents to solubilize the sulfentrazone prior to emulsification, in an aqueous glyphosate salt phase. U.S. Pat. No. 6,127,318 discloses emulsion formulations and an emulsifiable concentrate formulation of a triazolinone herbicide and glyphosate salt in which volatile aromatic solvents are used to solubilize the triazolinone herbicide.
The use of volatile organic and aromatic solvents in herbicide formulations which are to be sprayed onto crops, turf sites and the like are being discouraged by environmental agencies because of health, safety and environmental impact concerns. It would be most beneficial to eliminate volatile organic and aromatic solvents from herbicidal formulations while maintaining a stable, non-degrading liquid formulation.